Heart failure (HF) remains one of the largest unsolved problems in health care today and continues to increase in incidence and cost ($34.8 billion in US in 2008). Prognosis remains limited especially in patients with advanced heart failure. Transplantation is often the best option for patients with advanced HF whose hearts are not recoverable but is limited by many factors, primarily the small number of available donor hearts (<2500/yr in US). Use of current mechanical circulatory support (MCS) devices, though increasing, has also been limited due to the need for a major operation, restriction to Class IV patients, prolonged convalescence, and cost (over $100,000 US for the device itself). We have developed a novel MCS device (Symphony) that works synchronously with the heart, can be placed with a minor operation, and takes advantage of the proven benefits of counterpulsation. Symphony provides partial circulatory support to augment (not replace) native heart function. Recent clinical studies have provided strong evidence for the benefits of partial support. Also, experimental data strongly supports the benefits of partial support rather than complete unloading of the heart to promote myocardial recovery. The Symphony device is placed through an 8-cm infraclavicular incision similar to that used for placement of a permanent pacemaker. A short graft is sewn to the subclavian artery, connected to the pump, and then positioned superficial to the pectoralis muscle. Symphony is timed with the EKG to fill during systole and eject during diastole. Recent work in a Phase 1 study demonstrated subcutaneous EKG leads were as effective as epicardial leads for QRS detection and triggering. In this phase II study, we will complete development of the subcutaneous EKG lead system with integration to the Symphony device and lightweight, portable driver, and demonstrate efficacy, safety, and reliability of all system components. The development of a device that works synchronously with the heart, provides partial support (thereby promoting recovery), and can be placed with a pacemaker pocket operative approach may have a significant impact in expanding the role of circulatory support in the treatment of HF patients. The additional advantage of low cost (due to simplicity of design and a limited operative approach) may further expand the use of mechanical support with this device to currently large, unrealized, global markets.